energy transfer efficiency
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2021 ◽  
Author(s):  
Zhiyi Li ◽  
Ruifang Wang ◽  
Yangyang Zeng ◽  
Xiangyu Dong ◽  
Guanhao Liu ◽  
...  

Thermally activated delayed fluorescence (TADF) sensitized fluorescence is a promising strategy to maintain the advantage of TADF materials and fluorescent materials. Nevertheless, the delayed lifetime of TADF sensitizer is still relatively long, which cause heavy efficiency roll-off. Here we reported a valid tactic to construct fluorescent devices with low efficiency roll-off by utilizing the TADF sensitizer with reduced delayed lifetime. By construct the sensitization system, the energy transfer efficiency can up to 90%. The high energy transfer efficiency and the TADF’s short delayed lifetime result in the high sensitization over 95%, maximum external quantum efficiency of 16.2%. Meanwhile the TADF sensitized-fluorescent devices exhibit reduced efficiency roll-off with a “onset” current density of 23 mA cm-2. Our results provide an effective strategy to reduce the efficiency roll-off of TADF sensitization system.


2021 ◽  
Vol 2119 (1) ◽  
pp. 012123
Author(s):  
M Y Hrebtov ◽  
M S Bobrov

Abstract The paper presents a simplified numerical model of the hydrogen plasma generation process in a microwave resonant cavity. The model assumes electroneutrality and the prescribed electron temperature of the plasma, thus significantly reducing the computational cost. This allows for the parametric study in a wide range of operating pressures end electric field magnitudes (at a frequency of 2.45GHz). The prescribed model allows finding the effective range of operating pressures for the plasma generation. At low pressures, the collision rate is too low to effectively absorb all the emitted energy while at high pressures the electron conductivity drops which also reduces the absorption efficiency.


2021 ◽  
Author(s):  
Chang Liu ◽  
Jing Liang ◽  
Fangfang Wang ◽  
Chaojie Ma ◽  
Kehai Liu ◽  
...  

2021 ◽  
Vol 4 (8(112)) ◽  
pp. 83-89
Author(s):  
Hasan Shakir Majdi ◽  
Mahmoud A. Mashkour ◽  
Laith Jaafer Habeeb ◽  
Ahmad H. Sabry

The thermal coefficient of a solar photovoltaic (PV) panel is a value that is provided with its specification sheet and tells us precisely the drop in panel performance with rising temperature. In desert climates, the PV panel temperatures are known to reach above 70 degrees centigrade. Exploring effective methods of increasing energy transfer efficiency is the issue that attracts researchers nowadays, which also contributes to reducing the cost of using solar photovoltaic (PV) systems with storage batteries. Temperature handling of solar PV modules is one of the techniques that improve the performance of such systems by cooling the bottom surface of the PV panels. This study initially reviews the effective methods of cooling the solar modules to select a proper, cost-effective, and easy to implement one. An active fan-based cooling method is considered in this research to make ventilation underneath the solar module. A portion of the output power at a prespecified high level of battery state-of-charge (SOC) is used to feed the fans. The developed comparator circuit is used to control the power ON/OFF of the fans. A Matlab-based simulation is employed to demonstrate the power rate improvements and that consumed by the fans. The results of simulations show that the presented approach can achieve significant improvements in the efficiency of PV systems that have storage batteries. The proposed method is demonstrated and evaluated for a 1.62 kW PV system. It is found from a simultaneous practical experiment on two identical PV panels of 180 W over a full day that the energy with the cooling system was 823.4 Wh, while that without cooling was 676 Wh. The adopted approach can play a role in enhancing energy sustainability.


Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4869
Author(s):  
Mingkun Yang ◽  
Gexin Chen ◽  
Jianxin Lu ◽  
Cong Yu ◽  
Guishan Yan ◽  
...  

The electro-hydraulic servo pump control system (EHSPCS) is a volume control system that uses a permanent magnet synchronous motor (PMSM) with a fixed displacement pump to directly drive and control the hydraulic cylinder. The energy transmission law of the system is very complicated due to the transformation of electrical, mechanical and hydraulic energy as well as other energy fields, and qualitative analysis of the energy transfer efficiency is difficult. Energy transfer analysis of the EHSPCS under different working conditions and loads is proposed in this paper. First, the energy flow transfer mechanism was analyzed, and the mathematical and energy transfer models of the key components of the system were established to explore the energy characteristic state transition rule. Second, a power bond diagram model was built, its state equation and state matrix were deduced, and a system simulation model was built. Finally, combined with the EHSPCS experimental platform, simulation experiments were carried out on the dynamic position following and steady-state position holding conditions of the system, and the variation rules of the power of each energy characteristic state and the system energy transfer efficiency under different loads were obtained. The research results provide a foundation for the study of power matching and energy-saving mechanism of the EHSPCS.


2021 ◽  
Vol 9 ◽  
Author(s):  
Yuval Kolodny ◽  
Yossi Paltiel ◽  
Nir Keren

Photosynthesis, the process by which oxygen and sugars are created from water and carbon dioxide using the energy of the sun, is the basis of life on earth. To perform photosynthesis in changing light conditions, living creatures were required to adapt and develop sophisticated mechanisms to collect light efficiently. To understand these mechanisms, we studied the way blue-green algae (cyanobacteria), which perform photosynthesis in the sea, adapt themselves to changing light intensities, depending on the depth of the water. We found that in deep water where there is little light, the tiny antennas through which light is collected are bigger and longer. Surprisingly, although the energy is passing through a longer pathway, it actually passes faster. We found that cyanobacteria can control the energy transfer efficiency through their light-harvesting antennas by tuning the strength by which the antenna components are coupled to each other.


2021 ◽  
Vol 12 (2) ◽  
pp. 91-97
Author(s):  
K. N. Gorbachenya ◽  
V. E. Kisel ◽  
A. S. Yasukevich ◽  
E. V. Koporulina ◽  
E. A. Volkova ◽  
...  

Solid-state lasers emitting in the 1.5–1.6 μm spectral range are very promising for eye-safe laser range finding, ophthalmology, fiber-optic communication systems, and optical location. The aim of this work is the investigation of spectrosposcopic and laser properties of gain medium based on borate crystal for abovementioned lasers.Spectroscopic and laser properties of Er,Yb:YAl3(BO3)4 crystals with different concentrations of dopants were investigated. Polarized absorption and emission cross-section spectra were determined. The ytterbium- erbium energy transfer efficiency was estimated. The maximal energy transfer efficiency up to 97 % was obtained for Er(4 at.%),Yb(11 at.%):YAl3(BO3)4 crystal.The laser operation of heavily doped crystals with erbium concentration up to 4 аt.% (2.2^1020 cm^3) was realized. By using of Er(2 at.%),Yb(11 at.%):YAl3(BO3)4 crystal a maximal continuous- wave (CW) output power of 1.6 W was obtained at 1522 nm with slope efficiency of 32 %. By using of Er(4 at.%),Yb(11 at.%):YAl3(BO3)4 crystal a maximal peak output power up to 2.2 W with slope efficiency of 40 % was realized in quasi-continuous-wave regime of operation. The spatial profile of the output beam was close to TEM00 mode with M2 < 1.2 during all laser experiments.Based on the obtained results, it can be concluded that Er,Yb:YAl3(BO3)4 crystals are promising active media for lasers emitting in the spectral range of 1.5-1.6 pm for the usage in laser rangefinder and laser- induced breakdown spectroscopy systems, and LIDARs.


Author(s):  
Toshiki Fujii ◽  
Yuichi Kitagawa ◽  
Yasuchika Hasegawa ◽  
Hiroaki Imoto ◽  
Kensuke Naka

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